In view of the factors influencing the outburst of coal and gas, such as crustal stress, gas, physico-mechanical properties of coal rock, and geological structures, it is proposed that the processes of coal and gas outburst consist of three stages including formation and development of outburst source. Based on a typical outburst accident occurred in Nantong mine, the conditions for excitation and occurrence of coal and gas outburst are investigated by deductive method. The results indicate that the rock fractures generated from mining vibration and impact load are the excitation condition for outburst. The delay time for predicting outburst is obtained according to creep damage equation of coal saturated methane gas. The expressions for initial starting speed of outburst and gas critical pressure are obtained according to energy exchange relationship of outburst. Some difficult problems related to coal and gas outburst are discussed. It is shown that the main energy resulting in the coal and gas outburst is expansion energy. The extrusive gas comes from a few sources. The sources of outburst can be formed easily from geological structure region during mining.

In China, the researches on geological sequestration of CO2 are started, and the researches concerned with rock mechanics should be strengthened. For this reason, considering the reaction between gas, temperature and rock during CO2 injection in gas-bearing strata, a coupled thermo-gas-mechanical model is established in which CO2 is regard as a perfect gas, and Drucker-Prager yield criterion and non-tensile criterion are used; a relative two-dimensional FEM code is developed. A geological sequestration system which consists of an under-part reservoir and an upper-part caprock is assumed. Taking the system as the objective of numerical simulation, the changes and distributions of displacements, stresses, tensile and shear failure zones in the rock masses are analyzed under the conditions of different injection rates and different injection times. The results show that the optimal injection rate and injection time should be selected in order to ensure the stability of rock mass injected by CO2.

The shakedown and plastic behaviors of cohesive subgrade soil under cyclic loading are described. Based on the shakedown concept, various mechanical behaviors of subgrade red clay are discussed by repeated loading tests. The tests are performed with various conditions of subgrade soil, including different moisture contents, stress levels, numbers of repeated loadings and stress paths. According to the test results, the factors responsible for various mechanical behaviors of subgrade soil are analyzed in detail. The influence factors of the subgrade red clay mechanical behavior under cyclic loading and its permanent deformation trend as well as the mechanical behavior development rules are also analyzed systemically. The shakedown limit and critical stress level of subgrade red clay under cyclic loading with different moisture contents are presented. The plastic mechanical behavior can be divided into three phases: stable, failure and critical phrases, which are further divided into accepted condition and unaccepted condition. The critical stress level of subgrade red clay under cyclic loading is 41.8 %.

In process of coal-gas outburst, the coal mass forms a spherical shell itself which is the best form to resist outburst. Once the coal shell disintegrates, it loses carrying capacity; and in the high-potential coal-rock system, all kinds of energy corresponding to the outburst of a single coal shell are released immediately. According to the theory of plastic deformation localization which reflects the destruction characteristics of coal-rock, the equilibrium relationship of work and energy increments corresponding to deviatoric stress while coal shell deforms is educed; and the catastrophe model of destabilization and disintegration of coal shell is established. The mechanism of coal shell disintegration due to deviatoric stress is studied; the expressions of deviatoric strain energy at the destabilization moment, volumetric strain energy releasing amount are educed. The description of crushed coal and gas seepage form two-phase flow of gas-coal after porous gas outburst is given. The obtained analysis result can deepen the acquaintance with the combined action of three factors (coal, geostress and gas pressure) on coal-gas outburst.

Different geological structure characteristics of slopes lead to different deformation regulations and failure mechanisms of slopes; deformation regulation and magnitude of the same slope are different due to different excavation stages of slope; simple and static early warning index of slope monitoring obtained by engineering analogism is difficult to express the dynamic deformation features and slope regulations during excavation. A new study through and corresponding method to obtain adequate dynamic early warning indexes of slope monitoring during excavation are put forward, which are based on designed safety factor and failure mode of slopes. The study thought and method are applied to obtain the early warning index of left bank slope of plunge pool of spillway during excavation from 755 m to 740 m at Nuozadu Hydropower Station; and by comparing the value of early warning index obtained by the study thought and method with the value of field deformation monitoring, it is shown that the slope is stable during the excavation, which is in concordance with actual engineering so as to prove that the study thought and method are feasible and effective.

Periodic impoundment and drainage of the reservoir water will be implemented as planned after the Three Gorges Reservoir operation. The rock masses which constitute the reservoir bank will have lithology deterioration under “saturated water-air drying” water-rock circulation function, which will further constitute a great damage on bank stability. An experiment models the process of water-rock interaction on reservoir bank under reservoir water fluctuation with sand rock as a representative. And the result of the experiment is applied to numerical stimulation of the stability of reservoir bank under water-rock interaction with FLAC. The deterioration rule of sand rock’s shear strength under “saturated water-air drying” water-rock interaction of reservoir water is concluded, which provides a favorable evidence for the bank stability analysis.

Under plane strain condition, soil always exhibits softening characteristics and prominent stress peak due to strain localization. A traditional elastoplastic constitutive model is used to model uniform deformation of pre-peak; a deformation bifurcation theory involving non-coaxial elastoplastic model is employed to predict the stress peak; and a complex theory is introduced to describe the heterogeneous deformation of post-peak. By comparing the modeling results to experimental ones, it is shown that the softening characteristics of soil under plane strain condition can be truly described by presented approaches. Moreover, it is found that the most important key to predict the peak-stress is to introduce exactly a non-coaxial elastoplastic model into the classical deformation bifurcation theory.

In studying the motion law of rock-fall, the restitution coefficient is an important control parameter. It not only has something to do with stone’s speed and quality but also is closely related with stone and overlay layer’s physico-mechanical properties. However, currently there is no reasonable calculation theory about restitution coefficient which will still be a difficult problem in studying. According to Hertz contact theory and Cattaneo & Mindlin tangential contact theory, considering the elasto-plastic properties of materials, the calculation model of restitution coefficient both in normal and tangential impacting direction is studied. Then a specific formula is given, and some major factors about the coefficient are also illustrated. At last, by calculating an example and comparing with the existed conclusion, the theory is proved to be reasonable.

Based on the review of development and application of geotechnical ring shear apparatus at home and abroad, the course of ring shear apparatus design and its utilization are introduced. By summarizing the latest technical advances of ring shear test, the testing methods and technology, and the results of employing ring shear apparatus in the research fields are elaborated, such as the analysis of soil post-peak strain softening and residual strength measuring, the experimental study of the mechanism of shear band formation, the explanation of geological hazard mechanism, the assessment of interface shear strength properties of geosynthetics, and so on.

Parameters of asphalt concrete are related to the shaping method of specimen and test condition, therefore, the parameters are rather discrete and difficult to determine accurately. Based on immune GA and FEM, back analysis method is established to search for material parameters of earth-rock dam; and the corresponding calculation program is compiled. Combining with Maopingxi asphalt concrete core rockfill dam of Three Gorges Project, using monitoring data of the dam in the period of completion, parameters of asphalt concrete core of Duncan-Chang constitutive model are inversed. By the original monitoring information during the water level 139 m, the rationality of back analysis results is proved; an effective approach to determine the mechanical parameters of asphalt concrete is provided.

Strength characteristics of unsaturated soil of the landslide #1 in Xiaolangdi Reservoir are studied by using consolidation drainage test method with three-level continuous loading on the improved triaxial test instrument. The attention to the influences of oversized axial deformation (namely shear destruction) and shear expansion on the experimental sample of unsaturated soil is less paid in many present studies. The influences of shear destruction and shear expansion of experimental sample on matrix suction, shear strength and various characteristic relations of unsaturated soil are comprehensively analyzed. The results indicate high compactness samples counteract the trend of shear expansion by internal stress adjustment as increased negative pore water pressure, the matrix suction and strength of sample will increase in this process, and the influence of shear expansion on shear strength is similar with that on saturated soil. Furthermore, the shear destruction of sample in advance in multi-level test reduces the shear strength of the test within follow-up confining pressure, and more cohesive force and less internal friction angle than true values are obtained; the shear strength of the test within follow-up confining pressure after shear destruction is close to the residual shear strength.

A design method of layer thickness of perpetual asphalt pavement structure for heavy traffic is introduced and discussed. Based on limiting the tensile strain at the bottom of the asphalt layer and the vertical compressive strain at the top of the subgrade, the suitability of layer thickness is checked by two criteria. One is controlling the maximum surface deflection under the design load, and the other is controlling the modulus ratio between adjacent unbound aggregate base and subbase layer. The cumulative damage concept in predicting the fatigue (load-related cracking) and subgrade distortion is applied. Seasonal variations of material properties are considered by using equivalent modulus concept. A practical design of perpetual asphalt pavement structure for Guangdong to Wuzhou Expressway in Guangdong Province, China, is presented. Two key design issues related to fatigue cracking are discussed.

During Guankouya Tunnel construction, collapse of the section YK73+955-YK73+925 of right tunnel arose. Distribution of layered rock, unsymmetrical pressure, continuous rainstorm and cracked surrounding rock, inaccurate results of geological survey were discussed for reason of tunnel collapse. According to engineering geology and construction condition in-situ, ahead ductile grouting method and long and large tube shed method were analyzed; and ahead ductile grouting method was applied to tunnel surrounding rock consolidation successfully. In order to test consolidation effect, observational method of consolidated tunnel collapse zone was constructed; convergence displacement, vault crown settlement and inner forces of steel frame were measured. It is shown from measured results, ahead ductile grouting method is the optimization method for temporary support requirements against potential collapse.

The secondary stress distribution and deformation mechanism of excavated mining tunnel of -62 m, -74 m in Daye mine are studied. Firstly, the wall rocks of tunnel are grouped to different engineering geology groups; and the rock mechanical parameters of wall rock are determined based on geological investigation of field engineering and indoor rock mechanical experiment. The state of stress and strain of excavated tunnel is simulated by FLAC3D; and the wall rock deformation mechanism is also analyzed. The numerical simulation results are validated by convergence monitoring data of -74 m mining tunnel. The results show that the ranges of secondary stress distribution have differences corresponding to different wall rock conditions of mining tunnel; but the principal stress distribution transits from compressive stress centralized in mining tunnel sidewall to tensile stress centralized in mining tunnel vault and floor.

Concrete components have flaws, such as loose, hole, slit band and so on. These flaws not only lead to the change of acoustic velocity, but also have strong absorption and attenuation action to the acoustic wave. It is an effective method to detect engineering quality of concrete components by using acoustic velocity CT and attenuation CT combined detection technology. The acoustic velocity CT detection principle and the SIRT algorithm are described, the relationship between received wave signal frequency shift and attenuation absorption coefficient of medium is introduced. The relational expression of integral of dielectric absorption coefficient along the ray path with frequency shift parameters, which is suited to CT tomography inversion algorithm is derived. The results of acoustic detection of two kinds of concrete component models which are loose and have holes separately are processed by velocity CT and frequency shift attenuation CT. The results indicate that acoustic velocity and frequency shift attenuation combined tomography detection technology can obtain more accurate and reliable detection effects.

Negative skin friction is a comprehensive effect caused by additional settlement and dragload of pile induced by settlement of soil surrounding the pile. In order to study influences of different load at pile top on the behaviors of negative skin friction piles, field tests of negative skin friction behaviors of three identical piles with different loads at pile top are made in the same site. Test results show that load at pile top affects negative skin friction behaviors evidently. Additional settlement of pile induced by negative skin friction becomes larger, negative skin friction induced by soil surrounding the pile becomes smaller with the increase of load at pile top. Dragload induced by negative skin friction decreases and position of neutral point in pile moves up while load at pile top increases. It may be useful to the research for negative skin friction behaviors of pile.

The Cam-clay model revised by SMP criterion (MCC-SMP) is implemented into a commercial software by using return mapping algorithm based on two-stage schemes, which includes elastic predictor and plastic corrector stages. The algorithm for updating the stress is provided. A subroutine for implementing the algorithm is developed. Numerical simulations of triaxial compression, triaxial tension and plane strain tests are performed. The precision of the algorithm is verified by comparing predicted values with experimental results. By using the MCC-SMP model, three-dimensional finite element analysis of consolidation behavior of trial embankment on soft soil, in Australia, is carried out. The changes in pore pressure, settlement and lateral displacement are analyzed and compared with the observed data in situ.

The results with high precision are hard to achieve rapidly by means of conventional method such as theoretical analysis and numerical calculation; slope engineering is a highly complicated nonlinear system. A new prediction method based on Gaussian process (GP), as a probabilistic kernel leaning machine and a powerful tool for solving highly nonlinear problems, is proposed for slope stability evaluation. The GP model for slope stability evaluation is established and applied to the practical engineering. The results show that the method can find the nonlinear mapping relationship between classifications of slope stability and influencing factors easily. Furthermore, the reasonable, reliable and probabilistic results of slope stability evaluation can be obtained quickly by using the method. In conclusion, the method is feasible, effective and simple to implement slope stability evaluation and to provide a new way for fast design of slope engineering.

Tests of single pile under lateral load are modeled with FEM. The favorable effect of vertical load and the distribution of lateral soil resistance along pile under inclined load in layered soil are analyzed. The shaft resistance along pile under inclined load is greater than that of pile under lateral load within a certain depth below ground surface. Significant changes of lateral soil resistance at the surfaces of different soil layers along piles are observed. To a certain depth below ground surface, lateral soil resistance is nearly equal to the static soil pressure. Pile cap can reduce lateral displacement of pile efficiently. The free length of pile above the ground surface discussed herein is rather small, thus the P-Δ effect caused by vertical component of inclined load is small. The larger the shaft resistance along pile under inclined load, the bigger the vertical stress in the soil surrounding the pile. The vertical component of inclined load will increase the lateral bearing capacity of pile.

There is remarkable time-space effect in foundation pit construction in soft soil area. Creep model coupled by time hardening exponential function law and Druker-Prager yield and failure criterion can reflect the time effect in foundation pit construction. The parameters gained by fitting triaxial rheological test are used to simulate the deep foundation pit excavation. The influence of supporting time on deformation of retaining structure and internal force is analyzed. The results and the measured data are basically consistent. This method can offer references for design and construction of deep foundation pit excavation.

According to the data from more than 4000 synthetic boreholes of Hangzhou, the computer virtual site is attained by applying MapX, to which ABAQUS and some other mature softwares are integrated. Stress-strain analysis of the tunnel and lining is carried out, and the calculation of ground surface subsidence at any point on metro line No. 1 can be done after clicking the mouse. For reason that the calculation and analysis can be promptly proceeded at any time and any where with an instant comparison with monitoring data, from which the safe construction benefits much.

With a great deal of practice and theoretical analyses, the formula of determining horizontal foundation coefficient is obtained based on Baguelin’s formula. The power function simulating horizontal foundation coefficient is proposed by stepwise regression. Meanwhile, the analytical solution of anti-sliding pile is deduced under this kind of coefficient. Finally, through an engineering project, the design of anti-sliding by pressuremeter test is considered to be feasible; and the methods are worth researching and using widely.

The small scale model tests are designed to simulate the geogrid-reinforced subgrade adopted by highway construction to mitigate the differential settlements of differently treated foundations. Eight geogrid-reinforced subgrade models are studied, which include not putting geogrids, putting one layer of geogrids respectively in the bottom, the middle and the top of the subgrade, putting two layers of geogrids in the bottom and the middle, the bottom and the top, the middle and the top, and putting three layers of geogrids in the bottom, the middle and the top. The differential settlement of the model subgrade and the mechanical characteristics of geogrids are modeled to evaluate the effect of the geogrids reinforcement. The results of the tests prove that the geogrids reinforcement decreases the differential settlement of subgrade effectively; and putting two layers of geogrids in the middle and the top of the subgrade is the best reinforcement design.

Based on the grid data of the geographic information systems (GIS), the complex 3D spatial properties of slope can be fully considered in 3D limit equilibrium analysis. Through data acquisition, data processing, model establishing and stability analysis, the 3D safety factor can be calculated; and also the vector diagram of distribution of sliding forces on critical slip surface can be mapped. The result indicates that the distribution of forces on the slip surface is extremely uneven and shows obviously complex spatial properties.

The anisotropic characteristics of stratified rock mass are described by ubiquitous-joint model; the calculation method of safety factor based on ubiquitous-joint model is proposed; then the relationships between stratification dip angle , inclination and slope stability are analyzed by FLAC3D. The results show that (1) for bedding rock slope, when the angle between inclination of slope and rock stratum is small, the slope safety factor decreases, increases and then decreases with the increase of ; when 20－30°, the safety factor reaches the minimum value; while 60°, it reaches maximum value; different failure modes cause the variations of safety factor; when is large, the relationship curve shows the decrease then increase trend to gradually increase; according to the value of , the stratified rock slope can be divided into two types: 45° for strict bedding rock slope; 45° 90°for oblique stratified slope; (2) for reverse layered slope, when 45°, the relationship curve shows the trend of increase, decrease and then increase; the variation degree of each curve is almost the same with the variations of ; during decrease process, the slope of curve decreases gradually with the increase of , and the anisotropic characteristics of slope safety factor become small; when 45°, the relationship curve shows the trend of monotone increasing in nonlinear form; (3) the relationship between slope safety factor and shows that for bedding rock slope, the safety factor increases with the increase of ; for reverse layered slope, when is small ( 150°), the slope safety factor decreases with the increase of ; and with the increase of ( 120°), the slope safety factor increases while increases.

Deep mixing column is used widely in soft clay modification of highway engineering; but it is found that surrounding soils are disturbed and strength loses during deep mixing columns installation, which sometimes may induce embankment and pavement cracks. The paper focuses on the surrounding soil disturbance by deep mixing column installation which is still unclear. The cavity expansion theory is used to analyze stresses of surrounding soils, and then the Sekiguchi & Ohta model is used to analyze soil deformations, soil disturbance is evaluated by the disturbance degree of Hong & Onitsuka. The results ,which show that soil disturbance decreases with depth and distance increase, are in accordance with the change law of tip resistance measuring by cone penetration test.

Feasibility of explicit finite difference method(EFDM) to analyze the diffraction of seismic waves has been investigated. Based on EFDM, numerical models in 2D and 3D of Xiluodu underground cavern groups are generated; and detailed discussion of seismic response of underground cavern groups is carried out. Research shows that underground cavern groups are stable after the excavation; and the underground openings are safe under Tianjin hospital seismic waves arising from Tangshan aftershock. Comparison of numerical results between 2D and 3D of seismic response indicates that (1) 2D model is much more efficient than 3D one; (2) for underground caverns located in relatively intact and hard rock mass, 2D model can be used to predict the mechanical response of sections in the middle of caverns approximately; and 3D model has to be used to analyze the response of the sections near cavern portals.

Like soft fault, wave field would be separated into several fields if incident wave met joint interface, vibration strength then could be decreased. According to linear deformation joint model, wave transmission and reflection rules are studied. The result indicates that wave filed after vibration isolation is superimposed by transmission P wave and transmission S wave, of which the energy follows Zeoppritz equation, discontinuous displacement at joint interface causes wave attenuation. Higher normal stiffness can make larger coefficients of transmission P wave, while there isn’t connection between tangential stiffness and transmission P wave；both normal and tangential stiffnesses affect the transmission S wave, higher stiffness can make lower amplitude of transmission S wave which approximates to 0 gradually. Due to field interference after transmission, vibration amplitude of transmission composite wave will decrease, duration time will increase, and tail section of waveform will be distorted; total energy coefficient has no connection with joint stiffness, but it decreases with the increase of incident angle.

The plate anchor is a new anchor foundation of moored deep-sea offshore floating structures. When a plate anchor is buried in the clay and subjected to uplift force, the difference of excess pore pressures on anchor top and base results in suction force, which may be beneficial to improve the uplift resistance of anchor, especially when wind and wave loadings apply quickly. A finite element software, ADINA, is used to establish axisymmetric dynamic finite element model in effective stress form. The distributions of excess pore pressure and failure mechanisms of foundation under fast and slow loadings of circular plate anchor are studied. In terms of two typical normally consolidated clays, gault and kaolin, under fast loading condition, the solutions of ultimate bearing capacity factor agree well with results from plastic limit analysis. By means of parametric analysis, the effect of loading rate and anchor embedment on suction force and limit value of total tension resistance are discussed. Furthermore, the critical loading rates corresponding to fully drained and undrained conditions are proposed. Numerical results show that the total tension resistance under undrained condition may be three times of the value under drained condition.

The compressibility of rockfill materials is directly related to the safety and stability of projects, therefore, a good many groups of large scale uniaxial-confined compression tests are carried out on the rockfill materials for a certain pumped storage power station. The experiment results show that the compressive moduli of rockfill materials are higher; and the compressive indexes are much lower. More compression deformation will happen when the stress on the internal grain exceeds the value sufficient for particle breakage; and this stress is regarded as the transitional point of elastoplastic deformation. Specimens of a given rockfill materials, which are compressed from different initial void ratios, converge on a unique limiting compression curve(LCC). Moreover, the unloading rebound deformation of rockfill materials is elastic deformation because the deformation quantity is very small and linear. The compression state of rockfill materials is determined by the gradation no matter what the loading paths are, and the compressibility will decrease while the strength of parent rock increases or the initial void ratio and the content of mudstone decrease.

Based on a harbor construction project in Shanghai，the Mesri creep model is introduced to depict the creep deformation behavior of the soft ground. The viscoelastic parameters of Mesri model are determined by back analysis of field monitoring data. The objective function is established by least square method, and the variables are optimized. Taking into account the layered property of soft ground, iterative back analysis layer by layer method is used. Back analyzed parameters are substituted into the self-programmed software to calculate the settlement. The comparison between calculated result and measured result confirms the reliability of back analysis. At last, the long-term ground settlement after construction is predicted on the basis of the results of back analysis.

Pressure plate apparatus and GDS unsaturated triaxial apparatus are used to study the influences of compaction work, compaction water content, dry density, stress history and sample stress state on SWCC of unsaturated remolded clay. Through least-square method, Van Genuchten model, Fredlund tri-parameter model and Fredlund quadr-parameter model are employed to fit SWCC. The results show that each model can fit to the experimental data well. Through analyzing the influencing factors, it is found that not only physical condition of samples but also external stress condition can affect the shape of SWCC. The result shows the higher compaction work, higher compaction water content, higher dry density, longer stress history and higher net mean stress are, the higher air entry value is; and the water is more difficult to be discharged from soil samples. In high matric suction range, it seems that the influents of influencing factors on the shape of SWCC are reduced. Through comparing the residual water contents between Fredlund tri-parameter model and Fredlund quadr-parameter model, it is found that the residual water content has little effect on SWCC; it means the assumption that the residual water content is zero is right.

A novel gene expression programming (GEP) algorithm based on principal component analysis (PCA) is proposed and applied to predict slope stability. The PCA technology is utilized to preprocess the sample data and to reduce the input of prediction model, which thus improves the input factors and eliminates the correlation among the inputs. Then new sample data are input into gene expression to construct the prediction model. Applying the prediction model to predict the safety factors of 11 slope samples after learning other 71 samples, satisfactory result is obtained. Reserving the criteria that model judged by error value, Akaike’s information criterion (AIC)[12] is introduced; v-SVR algorithm, GA-BP network algorithm and PCA-GEP algorithm are compared respectively. The experimental results show the PCA-GEP algorithm is more accurate than v-SVR algorithm and GA-BP network algorithm. The engineering example indicates that the method is reasonable and feasible; and it provides a new idea for slope assessment. It can acquire slope safety factors quickly and accurately and evaluate the slope stability. It provides the decision basis for selecting economical slope design scheme.

In order to get the compression creep parameters of deep rock, the center hole deformation test of rigid bearing plate is carried out in site. The generalized Kelvin model’s instantaneous elastic deformation of deep rock under circular rigid bearing plate which bears the uniformly distributed load is deduced. Based on the viscoelastic theory, through Laplace transform and inverse transform, the numerical formula of the viscoelastic deformation is also obtained. Some creep parameters of soft rockmass such as instantaneous elastic modulus, viscoelastic modulus and coefficient have been achieved by way of the optimized inversion method; and the numerical formula is programmed. This method is applied to a slope project in dam zone, the compression creep parameters are obtained appropriately. This method uses the test data completely; and it is much better than the method which uses the surface displacement only.

Considering the compressibility coefficient as a variable, a differential equation about the permeability coefficient and consolidation stress is established based on the definition of consolidation coefficient, thus an expression of the relationship between permeability coefficient and consolidation stress involved with previous consolidation pressure is deduced for normal consolidated soft clay. Using experimental data, the presented expression is compared with the existing solutions and the test results. The research shows that the proposed expression can well reflect the characteristics of permeability coefficient with the variation of consolidation stress and is more approximate to the practice than those solutions without considering previous consolidation pressure. It will provide a more accurate method when predicting the rate of consolidated deformation in engineering practice.

A practical method of seismic wave input on three-dimensional viscoelastic artificial boundary is presented. Taking vertical plane wave as incident seismic wave, the loads applied on artificial boundaries can be expressed by displacements and velocities of input wave, which makes the earthquake easy to input. The difficulty that there is an unknown term which makes seismic wave difficult to input when the seismic wave input is made by spherical wave is overcome. The accuracy of the presented seismic wave input method is demonstrated by numerical examples.

Three-dimensional nonlinear numerical analysis of failure envelopes of bucket foundation under combined loading in heterogeneous soft clay is presented. The general-purpose finite element software ABAQUS is utilized, and numerical computations are conducted. Through the numerical analysis, the effect of strength heterogeneity of soft clay on failure envelopes of bucket foundation subjected to combined loading is investigated. It is shown that a failure envelope does hold in M=0 plane, but for H=0 and V=0 planes, the overall size of the normalized failure envelopes reduces as the degree of strength heterogeneity increases. For a given model test, the rationality of the numerical results computed by FEM is validated by comparing with experimental data.

Concerning the aseismic ability of rigid pile composite foundation, the equivalent linear method and its parameter values are verified by shaking table tests of rigid pile composite foundation; some practical cases are analyzed by means of 3D finite element method. The effects of layered foundation, soil modulus, pile diameter and pile length, cushion thickness and cushion modulus etc. on the earthquake responses of rigid pile composite foundation are discussed; and the aseismic mechanism of rigid pile composite foundation is studied. It is found that the equivalent linear method can adequately simulate the characteristics of the interaction between structure and composite foundation; the inertia force of the superstructure and the deformation of the free field have notable impact on the inner forces in piles; the inner forces in piles tend to remarkably increase for the existence of weak layers in soil.

Great and numerous risks will be encountered in the construction of rock tunnel; the tunnel boring machine(TBM) construction for deep-buried long tunnel is affected by various uncertain factors with random and fuzzy behaviors, which can’t be quantitatively analyzed by current methods. A synthetic evaluation index system for TBM construction risk is established by analyzing the factors that influence TBM construction. Based on the hierarchy of these factors, a model of two-stage fuzzy synthetic evaluation is proposed; and analytic hierarchy process(AHP) is used to determine the weight of each stage factor; fuzzy sets method is used to determine membership function; risk ranking is also classified. The proposed method is applied to the TBM construction risk in South-North Water Transfer Project; the simulation results show that the method is reasonable. The analytical approach and the results will be practical and helpful to other similar projects.

Shear stresses induced by different modes in engineering are primary analyzed theoretically and calculated by ADINA finite element program. The results indicate that when soil and pile are same, the shear stresses between pile and soil under the ultimate situations of different modes are different; the negative friction on pile induced by surcharge is maximum; and the negative friction of uplift pile is minimum; the friction of pile top induced by pressing pile and bottom-loaded pile is between them. Poisson’s ratio of pile ranged from 0.15 to 0.35, the shaft resistance increases accordingly. The recognition of the shear stress induced by different modes is helpful for understanding the interaction behavior and the mechanism of load transfer between pile and soil.

The importance of coupling analyses of slope runoff-unsaturated seepage and stress field is expounded; soil-water characteristic curve which is very important in unsaturated seepage analysis, including soil-water characteristic curve considering consolidation pressure is described; and some experiment results are simply introduced; the calculation method of slope runoff-unsaturated seepage is presented; the coupling calculation method of slope runoff-unsaturated seepage and stress field is put forward, and the finite element program is programmed; the difference between coupling and uncoupling are compared by an example. It is shown that the method presented is more practical and feasible.

More attentions are paid to effects of geological disaster of shallow gas on engineering construction. Recognizing the characteristics of gas permeability in reservoirs is the basis of taking effective measures to control the hazards. A homemade device to measure gas permeability is used to study the gassy sand encountered in Hangzhou Metro Project. Results show that the shallow gassy sand has excellent permeability, and its permeability can reach 2 960×10-3?m2. The Darcy law can be used to describe gas permeability law in sand. The increasing water content of gassy sand has little effects on its permeability in lower saturation degree. With the increase of saturation, gas permeability gradually weakens; and gas permeability coefficient sharply reduces until completely tight when the saturation degree is more than 80 %. Comparing with the dry density, influence of the saturation degree on gas permeability of shallow gassy sand is more significant.

Taking the remolded soil after consolidation and the samples under special stress state by special stress path as the objects, the effect of stress path circumgyration on shear modulus and the trend of shear modulus along with strain under condition of small strain are studied. Under the condition of small strain, (1) the initial value of shear modulus increases along with the increase of the angle between experimental stress path and recent stress history. If the two directions were entirely reverse, the effect of stress path circumgyration on shear modulus is the most; if they went all the same way, the effect is the weakest. (2) Secant shear modulus is always greater than tangent shear modulus; shear modulus attenuates along with the increase of shear strain, and the attenuation rule of shear modulus keeps the same. However, different stress paths and strain ranges lead to different attenuation ranges. Under the condition of small strain, anisotropy is shown; however, the anisotropy degree decreases with the increase of shear strain, and the approximately isotropy is got. At the same time, the effect of stress path circumgyration on shear modulus decreases gradually along with the increase of shear strain.

The general Peck empirical formula is used for calculating vertical displacement of soil at the plane of buried pipeline caused by pipe jacking construction. The force model of buried pipeline is simplified. Based on Winkler foundation model, calculation methods for calculating ultimate and theoretic bending moments and pipeline deformation affected by pipe jacking construction are obtained. Through analyzing examples the solution is compared with Attwell’s solution and Wangtao’s solution. The influences of soil condition, material of pipeline, buried depth and diameter of pipeline on the force of buried pipeline are discussed. The results show that the method can be applied to any soil condition and predict bending moment of buried pipeline well; and the maximum bending moment of the pipeline will not be underestimated. Under the same condition, the deeper of buried depth of pipeline is, the larger bending moment of buried pipeline is. However, the effect of pipeline depth is not obvious except on the pipeline near the positions of maximum positive bending moment and maximum negative bending moment. The ultimate bending moment and influence zone of pipeline increase with the increase of bending stiffness of pipeline. The larger diameter of buried pipeline is, the larger bending moment of buried pipeline is.

Based on the field test in Suining－Chongqing High-speed Railway, the dynamic responses of pile-plank embankment, on which a disperse impetus locomotive CRH2 with high speed is running, are studied; the relationship between the dynamic responses and the train speed is analyzed; the changes of dynamic stress along the depth of subgrade is analyzed. The analyses indicate that the displacement, acceleration and dynamic stress increase in various degrees while the train speed increases, and they increase first and then decrease at the critical velocity. The dynamic stress attenuates fast with increasing depth of the subgrade, while increasing the depth, dynamic stress is closer to the static stress. Dynamic stress at pile-bottom soil is biggish, and pile structure expands the depth of the dynamic response of roadbed and improves the stress of the roadbed soil.

The frost-heaving and thawing-settlement of roadbed are often met in Qinghai-Tibet Railway, especially in salty soil area. Thermal characteristics of salty soil are researched by TG-DSC technique. The results show that soluble salts have great influence on thermal characteristics of salty soil; water content gets higher, phenomena gets acuter. Freezing force depends on water content and freezing temperature; the more water content or the less temperature is, the more intensive of freezing force is. The conclusion has guiding significance for mastering the characteristics of frost heaving and thawing-settlement in salty soil area of Qinghai-Tibet Railway.

Due to the extremely complicated boundary conditions of saturation flow of tailings dam, the calculation results adopting two-dimensional simplified theory may be greatly different from the measured results. A simple accurate calculation method to forecast saturation line is needed urgently. Based on deep analysis of affecting factors of saturation line in tailings dams, the superposition influence function is established; and the saturation line matrix prediction method is brought forward to predict the saturation line. According to the daily observation of saturation line, the water level of observation well and reservoir water level curves are attained by polynomial regression analysis.

A slope stability evaluation method based on particle swarm optimization (PSO) and least square support vector machine (LSSVM) is proposed. The method not only has the excellent characteristics of solving speed fast and describing nonlinear relationship easily of LSSVM, but also has the characteristic of fast global optimization of PSO. PSO is used to search the optimum parameters of LSSVM; then the optimal model is applied to predict the slope safety factor. The results show that the method is reasonable and feasible.

On the basis of Biot’s dynamic theory, a row of rigid piles is used as a barrier for SV waves in homogeneous unbounded saturated soil. Based on wave function expansion method, the potential functions of scattered waves are expanded into Fourier-Bessel series; and a set of cylindrical coordinate systems is utilized in such a way that it allows to solve the problem of multiple scattering; the solution is determined by imposing continuity and equilibrium conditions at the soil-pile interfaces. A parametric analysis is conducted to study the influence of the pile spacing and soil permeability on the isolation effect. The results show that the pile spacing has a significant influence on isolation effect in saturated soil. Comparing the isolation effect in elastic soil there is a different isolation effect for SV waves in saturated soil. As the permeability coefficient of saturated soil decreases, the isolation effect of a row of rigid piles is improved.

In order to meet the engineering requirements of the design of backfilling waste rock, which will be implemented during surface mining to underground in the pit III of Sijiaying iron mine, a large size in-situ permeability test in the test-pit near the pit III is performed. Digging three large size test-pits, an injection test is performed in each test-pit with different ranges of particle sizes and layer thicknesses. The permeability coefficients are measured, the size composition of rock and soil aggregates(RSA) is tested; and the mean particle diameter and the heterogeneous degree are figured out. Through the research, the permeability coefficient of RSA increases with the increase of mean particle diameter and the heterogeneous degree respectively. Accordingly, decreasing mean particle diameter and heterogeneous degree can decrease permeability of waste rock effectively.

Blasting ramming dynamic consolidation is a new foundation treatment method which combines explosion effect of strip dynamite with surcharge to change the structure of soft soil installed with drainage in advance. In this process, the excess pore water pressure surges, dissipates and the consolidation of the soil is accelerated under the surcharge. Experiments are carried out in Heshun-Beijiao highway to prove the effect of this method. Based on settlement data, design parameters are calculated; and results show that the explosion effect of the experiment is equal to 3.2 m surcharge. The vibration problem caused by explosive ramming is also analyzed.